The Spurs coach worked as a scout for his compatriot at Porto, Inter Milan and Chelsea, but says that he does not "lose any sleep" about cutting ties.
"I don't lose any sleep," the Spurs boss told reporters. "Our break-up point was because I was full of ambition to give him something extra and I wanted further involvement from the job I was doing at that time.
"I felt I could give him much more. But he didn't feel the need for somebody near to him or in another position as an assistant, and because of that it was decided that it was time, after Inter Milan, to continue our careers [apart]."
Although Villas-Boas admits that the duo had a "great personal and professional relationship", he no longer considers him a friend.
"I don't think we need explanations. But our relationship broke down. I think we have the mutual respect for each other and we understand what we have been through cannot just disappear, but it's not like it was before," he added.
Spurs will take on Chelsea on home turf this Saturday.